The world’s first vaccine against Ebola virus gained conditional approval from the European Commission in November. Merck’s Ervebo vaccine has already been given to hundreds of thousands of people to help control the current outbreak in the Democratic Republic of the Congo (DRC). The approval will now speed up licensing by African country regulators and enable rapid patient access in at-risk countries.
The vaccine is a vesicular stomatitis virus–based vaccine expressing the glycoprotein of a Zaire Ebola virus (rVSV-ZEBOV). It has been given as one dose during an outbreak to individuals who have been in contact with infected people and the contacts of those contacts, as well as to front-line healthcare workers, in a so-called ring vaccination strategy under an expanded-access compassionate use protocol. Preliminary analysis of 90,000 vaccinated individuals in DRC estimates an efficacy rate of 97.5% when individuals are exposed ten days or more after vaccination, according to World Health Organization (WHO) data.
Another vaccine, made by Johnson & Johnson, began testing in DRC in November. The company in the same month applied for European approval. The Johnson & Johnson vaccine regime consists of two vaccines: an adenovirus type 26–vectored vaccine encoding the glycoprotein of Zaire Ebola virus (Ad26.ZEBOV) and a booster shot with a modified vaccinia Ankara–vectored vaccine encoding glycoproteins and a nucleoprotein from several types of Ebola virus (MVA-BN-Filo) given 56 days after the first immunization. The trial will vaccinate at-risk individuals living close to, but outside, the current outbreak zone in an effort to prevent virus spread.
The WHO says the Merck vaccine meets the organization’s quality, safety and efficacy standards, which allows United Nations agencies and the vaccine alliance Gavi to stockpile the vaccine for future outbreaks.